(1) Field of the Invention
The present invention relates to a process for treating a coil end upon automatic winding of the coil used for a motor, relay or transformer, by which each of a portion of the wire (i.e. electric wire) at the front end of the coil and a portion of the wire at the rear end of the coil is bound to a corresponding terminal formed on a winding object.
(2) Description of the Related Art
So far, for example, in case of a multi-spindle automatic winding device of coil, each of the portion of the wire at the front end of the coil and the portion of the wire at the rear end of the coil as insulation-treated has been bound to a corresponding metal terminal formed on a winding object such as a coil bobbin by winding each of the wire around the corresponding terminal with about three to six turns.
An example of the winding object is shown in FIG. 6. The winding object 1 is provided with a terminal 2, to which a portion of a wire at the front end of a first coil is bound, and a terminal 3, to which a portion of the wire at the rear end of the first coil is bound, with each terminal protruding upward. The winding object 1 is further provided with a terminal 4, to which a portion of a wire at the front end of a second coil is bound, and a terminal 5, to which a portion of the wire at the rear end of the second coil is bound, with each terminal protruding upward.
In general, a portion of the wire at the front or rear end of the coil, which is bound to the corresponding terminal of the winding object, has been electrically connected to the terminal by arc welding in a downstream process. In the arc welding process, a high voltage electricity is applied between an electrode and a terminal to be welded so as to generate an arc and high heat simultaneously, by which the portion of the wire at the front or rear end of the coil and the terminal are melted and joined together, thereby the electric connection is attained.
In a conventional process for treating a coil end upon winding of the coil as described above, the portion of the wire at the front or rear end of the coil is electrically connected to the terminal by arc welding. In an arc welding, since the arc tends to blow to a position at which the electricity is easily conducted, therefore it is an important subject how to blow a stable arc to a portion to be welded.
However, in the conventional process for treating a coil end as described above, an insulating coating of a wire (i.e. electric wire) affects an arc restraining the arc from blowing, resulting in an incomplete welding. As a result, there has been a possibility that the coils thus manufactured might include a defective coil, which cannot be used for electrical conduction, thereby deteriorating the reliability of the product.